Sperm count in men from North America, Europe, Australia and New Zealand declined by 50-60% between 1973 and 2011, according to a new study from the Hebrew University of Jerusalem. Surprisingly, the study, which analysed data on the sperm counts of 42,935 men, found no decline in sperm counts in men from Asia, Africa and South America, although there was limited data from these areas.

Overall, this is a very disturbing report. There has been a longstanding debate among scientists as to whether sperm counts have decreased or not. But what’s different about this study is the quality of the analysis. It was done in a systematic manner, accounting for several of the problems that had affected previous studies, such as the method used to count sperm and comparing studies performed sometimes decades apart. As such, most experts agree that the data presented is of a high quality and that the conclusions, although alarming, are reliable.

So what is going on? There has been concern for a number of years about an increase in abnormalities in male reproductive health, such as testicular cancer. The decline in sperm counts is consistent with these increases and this adds weight to the concept that male reproductive health is under attack and is declining rapidly.

In fact, if the data on sperm counts is extrapolated to its logical conclusion, men will have little or no reproductive capacity from 2060 onwards. The most rational explanation for the decline in male reproductive health is the changes in the environment. Current research suggests that the male foetus is particularly susceptible to exposure to pollutants and so changes that occur early in foetal life can have a very significant effect on the adult.

What can be done?

The simple answer is that we need much more research to find out why this decline in sperm count is happening. We cannot be complacent about the potential negative effect on fertility and must now urgently rally to substantially increase the research effort into male reproductive health.

Also, although the prevailing evidence shows a decline in reproductive health, not all studies show this; there are some geographical differences. It will be critical to determine what the key differences between geographical regions are – such as genetic differences and exposure to specific pollutants – so we can then examine treatment strategies to limit these negative effects.

If it’s the foetus that is mainly affected, what can the adult man do? Even in adults, exposure to chemicals, such as bisphenol A, which are thought to affect fertility, can have a negative effect, so men should limit their exposure to toxic chemicals. This includes stopping cigarette smoking. Also, a healthy lifestyle is very important as there is a known link between obesity and reduced sperm count.

]]>https://sciblogs.co.nz/guestwork/2017/07/31/sperm-count/feed/0Common pesticides can harm bees, but the jury is still out on a global banhttps://sciblogs.co.nz/guestwork/2017/07/01/neonicotinoids-bees/
https://sciblogs.co.nz/guestwork/2017/07/01/neonicotinoids-bees/#respondSat, 01 Jul 2017 00:07:03 +0000https://sciblogs.co.nz/?p=243428By Phil Lester, Victoria University of Wellington

Some of the world’s most widely used pesticides can be harmful to bees, according to the first large-scale studies aimed at measuring the impact of compounds called neonicotinoids on bees’ health. But the effects vary widely between different compounds and different countries, suggesting that more regional research will be needed to clarify the exact scale of the problem.

Neonicotinoids, which are typically coated onto seeds before planting rather than being sprayed onto crop plants, were developed with the aim of harming only those animals that eat the plants. But they are also found in the pollen and nectar of treated plants, potentially affecting beneficial organisms like bees.

Two papers published today in the journal Science report that neonicotinoids have negative effects on honey bees and wild bees in realistic field experiments. But the results are mixed and far from conclusive.

The concern about neonicotinoids prompted the European Union to impose a temporary moratorium in 2013 on the use of three key pesticides. In contrast, New Zealand’s government has joined with Australia in not imposing a ban. I think our governments have made exactly the right decision at this time.

Study confirms negative effects

This is consistent with many previous research findings showing that feeding on large amounts of neonicotinoids can be fatal to honey bee workers and queens.

For bees given a smaller dose, their foraging becomes less efficient. They undertake reduced hygienic behaviour in the hive and their immune system seems to be impaired. And their tolerance of other stressors bees experience in their environment, in this case a fungicide, is reduced.

The new Canadian study shows that field-realistic exposure to neonicotinoids can substantially reduce honey bees’ health.

Other results mixed

The other study, led by Ben Woodcock of Britain’s Natural Environment Research Council, describes research done on three different bee species in three different countries. It also attempted to use field-realistic exposure to neonicotinoids. Populations of honey bees, bumble bees and a solitary bee were followed in the United Kingdom, Hungary and Germany.

The team examined two neonicotinoid pesticides, and found a fascinatingly mixed bag of results. Both pesticides resulted in significantly reduced numbers of honey bee eggs being produced in Hungary. But exposure to both pesticides in Germany resulted in significantly more eggs being produced. Neonicotinoids also seemed to result in higher numbers of workers surviving winter in Germany.

In Hungary, fewer worker bees survived winter after exposure to one pesticide, but not the other. Similarly, in the United Kingdom, there were mostly negative but some positive effects of exposure to the different neonicotinoid pesticides.

The take-home message is that different neonicotinoids can have different effects, which can be very specific to the country of use. After reading these results, if I were a grower in Germany, I might start to question the European Union’s temporary moratorium.

Country-specific data needed

These studies highlight the need for data to allow countries like New Zealand and Australia to effectively manage the use of neonicotinoid pesticides. We need to know the effects of neonicotinoids in our specific environmental conditions and in the way we use them.

We also need to know what the effects would be if we took this group of pesticides away. I’ve read reports that growers in the UK have had to revert to broad-spectrum pesticides that are considered worse for the environment and mean they cannot grow certain crops.

In 2013, the Australian government undertook a review of neonicotinoids and the health of honey bees. This concluded that “the introduction of the neonicotinoids has led to an overall reduction in the risks to the agricultural environment from the application of insecticides”.

The review found little scientific evidence to show that the current use of neonicotinoids in Australia causes widespread harm to honey bees. The review stated that “the introduction of the neonicotinoid insecticides has brought a number of benefits, including that they are considerably less toxic to humans (and other mammals) than the organophosphorus and carbamate insecticides they have significantly replaced”.

Bees are up against it

Honey bees in New Zealand have a plethora of known and scientifically demonstrated threats. These include invasive blood-sucking mites, and the deformed wing virus, which has been described as a key contributor to the collapse of bee colonies around the world.

New Zealand’s bees have bacterial pathogens like American foulbrood that results in beekeepers having to burn their bees and hives. Fungal diseases are widespread. We also have management issues with the higher-than-ever numbers of managed hives, which are often managed poorly and often overstocked. These are real and known issues affecting our honey bees now. We have data on these problems that can guide their management.

The new research will doubtless lead to calls from some quarters for Australia and New Zealand to ban neonicotinoid pesticides. I hope that the New Zealand and Australian governments act on studies like those published today, but I would be disappointed if that action was anything other than evidence- and science-based. Let’s gather the data specifically for each country, and then make a decision on whether and how to use these pesticides.

Two papers were published today in the prestigious journal Science reporting negative effects of neonicotinoid pesticides on honey bees and wild bees in realistic field trials. Neonicotinoids are arguably public enemy number one for bees in the mind of the public, but the actual science behind the headline-grabbing stories is far from conclusive about the impacts of these pesticides.

Neonicotinoids are a class of insecticides which have a more specific action against insects and a lower environmental impact than more traditional organophosphate pesticides. As they are taken up by plant tissues, including through the coating of seeds to protect the resulting seedling as it grows, much lower rates can be used. In this sense, they are widely held to be far superior to traditional organophosphate pesticides which are broad spectrum and are applied at higher rates than neonicotinoids to suppress pest insects.

Several studies have reported a negative effect of neonicotinoid pesticides on the health and behaviour of bees in laboratory experiments. This has led to concerns among scientists, the public and policymakers about the harmful effects of neonicotinoid use. Most of their effects, however, have been reported as sub-lethal, in other words, they don’t directly kill the individual bees immediately, but their long-term effects on behaviour or physiology could affect the health of bee colonies and insect populations. A big limitation to date has been that large-scale field trials to test the ‘real world’ effects of the use of neonicotinoids are very difficult to run, and so clear evidence of the effects has been lacking.

I am aware of only four realistic field trials published prior to today. Two studies looked at the effect of real-world neonicotinoid treatments on honey bee colonies and found no negative effect (Cutler et al., PeerJ, 2014; Pilling et al., PLOSOne, 2013). Another study found a negative impact on individual honey bees, but found that the colonies were able to compensate for the loss of these individual bees so that there was no net effect (Henry et al., Proc Roy Soc B, 2015). The fourth study has probably been the most convincing to me to date, finding a negative effect on wild bumble bees and solitary bees, but no effect on managed honey bee hives (Rundlöf et al., Nature, 2015).

Two new studies have been published in Science this week, by Woodcock et al and Tsvetkov et al. The main take home message from these two studies is that they are the first to document negative effects on honey bee colonies from real-world neonicotinoid exposure. So in terms of the number of studies evaluating the hypothesis that real-world use of neonicotinoids have colony-level effects on honey bees, the score in my calculation now stands at 2 for, 4 against. This is how science proceeds: we are likely to continue to see scientific tussles back and forth while we narrow in on the actual suite of factors that affect honey bee health.

Three European countries, three different results

However, when you look a little closer at these new studies, the results are not quite so straightforward. In the Woodcock et al. study, the trial was repeated in three countries. When we look at the honey bee data, where nine parameters were assessed for each of two neonicotinoids, no negative effect was detected in Germany (they actually found a positive effect), two negative effects were detected in Hungary, and two negative and one positive effect were found in the UK.

Even when negative effects were found, this appears to only be linked to one of the two neonicotinoid treatments compared to the control. But all three treatments (the control and the two different neonicotinoid treatments), had different fungicide treatments applied with them, violating the basic scientific rule to control all variables apart from the one you are interested in, or at least account for these other variables. This study, unfortunately, has confounded neonicotinoid treatment with fungicide treatment, so it is not really possible to draw many conclusions on neonicotinoids alone. So my personal opinion is that the effect on honey bees in this study is ambiguous at best.

In terms of wild bees, the evidence is more convincing. Both bumble bees and the solitary Osmia bicornis bees showed reduced reproductive output with higher levels of neonicotinoids. This was based on total neonicotinoid residues in nests, which was not correlated with experimental treatment (i.e. the aim of the experiment to delimit three different exposures to the bees did not work), and included another widespread neonicotinoid not tested in this study. This part of the paper is an important piece of evidence of the negative effects of increased neonicotinoid exposure on the reproductive capacity of wild bees.

Canadian study clearer

The second paper by Tsvetkov et al. is more convincing about the effect of neonicotinoids on honey bees. It starts with an assessment of the exposure of bees to agrichemicals in cropping and non-cropping areas. Like the other study, their exposure was not directly linked to the treatments of the crops in the fields in which the hives were placed, but rather reflected exposure from a much wider surrounding area. Then, based on the levels of the neonicotinoid clothianidin found from these exposure trials, they assessed the effects of feeding pollen contaminated at these levels to honey bees.

The neonicotinoid treatment reduced the longevity of workers (which can hasten colony decline), reduced hygienic behaviour by the colonies (which affects susceptibility to pathogens and parasites), and increased ‘queenlessness’ (a state where the hive is without an active laying queen, so reproductive output stops until a new queen is raised or installed). They also show that combining neonicotinoids with a particular pesticide increased lethality of the neonicotinoid (which could explain some of variability in results found in the other paper).

In terms of the balance of evidence for all six papers now published, one study shows negative effects on colonies, one is ambiguous and four show no negative effects on honey bee colonies. We shall have to continue to wait to see what further studies reveal.

But what about New Zealand?

What does this mean practically for New Zealand? Nothing really at this stage. We can see that there is no net effect of neonicotinoids on honey bees in New Zealand, as numbers of hives continue to rise. We now have something close to 850,000 hives, up from just under 700,000 this time last year and up from 300,000 15 years ago. However, there are localised effects of pesticides on hives. This is usually due to applications of non-neonicotinoid pesticides, rather than neonicotinoids. The colony deaths experienced with these more traditional pesticides are much more severe than the sub-lethal effects of neonicotinoids on overall colony reproductive fitness.

There are two important caveats to this. Firstly, wild bees in the northern hemisphere have been found to be at greater risk than managed honey bees. This could be happening in New Zealand too (or rather, it is unlikely that this is not happening), with native ground nesting bees and introduced bees like the ever-popular bumble bees present at these agricultural sites throughout the year and therefore likely to be more exposed to these pesticides. However, yet again, these wild bees would be affected much more severely by organophosphates than neonicotinoids.

Secondly, the finding of a synergistic effect is really important. Agrochemicals are purposely combined at times for the sake of efficiency, and inadvertent combinations can occur through exposure from different sites, spray drift, or accumulation of residues. The effects of these many combinations of agrochemicals are rarely tested, and are not usually considered in product registrations. Maybe it is time we should start thinking about this.

We don’t have evidence of population-level bee declines in New Zealand due to agrochemicals yet, but do we need to wait for clear evidence of a decline before we start thinking about and testing for some of these potential synergistic effects? We have no long-term monitoring of any bee or other insect pollinator populations apart from managed honey bees; maybe it is time we got some programmes like this up and running.

It is good to see more thorough studies on neonicotinoids in the field coming through, providing further support for the hypothesis that these chemicals negatively affect wild bees. It could be that this is the start of a wave of studies that start to build a consensus that these pesticides also pose an undue risk to honey bee populations, or it could be that further studies reveal this specific threat to be minor compared to other pressing issues like organophosphate pesticides, loss of forage resources, climate change, and pests and pathogens. Sometimes in science you just need to sit and wait as the studies accumulate!

More bad news for bees this week. Honeybees around the world are struggling in the face of disease and insecticide threats. In New Zealand we have Varroa mite, that increases costs for beekeepers, destroys unmanaged beehives and vectors viruses, making them more virulent. Overseas, Colony Collapse Disorder and pesticide-threats are adding to the woes Varroa brings, meaning bee numbers appear to be declining.

The loss of pollination capacity due to the loss of bees should be a big issue for all of us. In New Zealand, honeybees are estimated to support 35% of our primary sector, contributing $5.1 billion in export revenues (Laas, F., Foster, B. & Newstrom-Lloyd, L. Report to the Select Committee on Pollinator Security in New Zealand. (2011)). Beyond this, the pollination of the beans and fruit trees in your garden and parks, is dependent to some extent on bees. New Zealand would be poorer, both environmentally and economically, without bees.

A paper published this week adds to the problem. It finds that bees that consume pollen with high fungicide levels have an increased probability of high rates of infection of Nosema ceranae (Pettis et al, PLOS One 8:7 e70182). Nosema is a unicellular parasite (microsoporidian) of honeybees, and have been linked to Colony Collapse Disorder. High rates of Nosema are detrimental to bee and hive health. The finding that fungicide dose affects Nosema infection is surprising, because fungicides should be perfectly safe for bees. The doses here are not high, but they seem enough to disrupt hive health, perhaps producing honeybee declines.

The bad news is that all but one of the fungicides found to have an association with Nosema are used in New Zealand. We also have Nosema.

Let’s be clear here; this is not a black and white issue. Agrichemicals are key parts of our production systems, and are not, in the main, used indiscriminately. Now there is a balancing act: ensuring bee health while maintaining efficient production. This is not going to be an easy equilibrium to maintain.

Perhaps more pressing is the need to investigate more sensibly the affect of agrichemicals on bees. Determining the lethal dose (the dose at which a bee dies) of a chemical, does not determine if sub-lethal does have effects on the behaviour or health of the whole hive. Bees are incredible animals because of their hive behaviour, their division of labour and their sociality. This also makes them sensitive in ways that non-social insects are not. We need to know more about the impacts of agrichemicals, used validly to improve our primary production output, on the remarkable super-organisms that are bees.

The authors of this latest research reviewed 17 human studies and 223 studies of nutrient and contaminant levels. They conclude that the published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods; although consumption of organic foods may reduce exposure to pesticide residues and antibiotic resistant bacteria.

So what is the difference between organic and conventionally produced food? Well, according to the NZFSA, organic agriculture is “a production system that avoids or largely excludes the use of synthetic fertilisers, pesticides, growth regulators and feed additives.”

They go on to say that, “organic agricultural practices are premised on a philosophy of farming articulated through four basic principals – health, ecology, fairness and care. For consumers who purchase organic foods often health, taste and environmental benefits are important considerations in their food choice.”

This latest review paper found that organic produce had a 30% lower risk for contamination with any detectible pesticide residue than conventional produce. However, in New Zealand, the Ministry for Primary Industries state,

“The use of pesticides, herbicides, fertilisers, and veterinary medicines is strictly regulated in New Zealand, such that any residues present in food due to the use of these agricultural compounds are at levels that present notional zero risk to consumers. The term ‘notional zero risk’ is used to describe the risk associated with consuming levels of substances below the acceptable daily intake (ADI) which is the level at which a substance can be consumed every day for a whole lifetime without noticeable effect.”

From a nutritional perspective this latest review paper showed there is little difference between organic and conventionally produced food. There were no significant differences in vitamin content, and although phosphorous and total phenol content of organic foods were higher, the difference was of little clinical significance.

Organic produce can be considerably more expensive and the authors of this latest research conclude that despite the widespread perception that organically produced foods are more nutritious than conventional alternatives, they did not find any robust evidence to support this perception.

For anyone concerned about pesticide residues, consumption of conventionally produced fruits and vegetables has not been found to pose any risk to health – but washing and peeling fruits and vegetables will reduce exposure. For more information check out this Cancer Society information sheet.

The benefits of consuming fruits and vegetables certainly outweigh any risk, and we should all be consuming at least five portions a day of this important food group